Manufacture of electric filaments.



. 1,109,887- Il't Drawing.

mzrnn STMM N CE CARL Arms van wmssacn, or vmnim, AUSTRIA-HUNGARY;

MANUIKACTURE or nanometre FILAMENTS;

, To all whom it may concern Be it known that I, Dr. CARLIAU II v'ori TELSBACH, a subject of the Emperor of Austria-Hungary, residing at V enna, Austria-Hungary, have invented or discovered a certain new and useful Improvement in the Manufacture of Electric F1laments,of which thefollowing is a specification.

In a' companion application, filed of even date herewith, No. 728,356 I have described certain methods for eliminating from fila.

ments of osmium or osmium alloy, either alone or coated, or otherwise; associated with metallic o'xids', the occluded gases absorbed by the osmium during" a certain stage of its formation. The present application relates to the filaments themselves produced by the practice of the methods referred to, or in' any other manner; I find that lamps made of filaments from which those' gases have been eliminated, which will not remain occluded in the osmium when the filament is brought to White incandescence, have a sub' stantially perfect and practlcally lasting void of said gases, I proceed as follows:

' When the filament for th'ebulb is to be of pure osmium, I mount it therein fusing the bulb tothe portion'of the'lainp' which:

carries the filament and leading-in wires,

taking care to first carefully clean the'bulb itself. I then. fill the bulb with a dry gas,

such as nitrogen which will not attack the osmium,- While hot, and then, while highly heating the bulb, I exhaust the gases there from. Thereupon, I pass a current of dry reducing gases (as, for instance, dry car bonaceous' gases) through the bulb and again exhaust, repeating this latter alternate gas-rinsing and exhaust ng operation sevei'altimes. Finally, when; after the last gasrinsing, the subsequentexhaustingoperation has considerably loweredthe'pres'sure in the bulb, I pass an electric current of says or 4: watts'per candle, through the filament, sufficient-to bring it to a correspon'dingfllumi nosit and I thencomplete the vacuum.- 'The lament thereupon begms'to slowly give ofi its occluded gases, and its luminosity"in creases until it attains adazzlingwhiteness,

As soon as it completely ceases to'give ofi Specification 'of iettei's Patent. Application filed August 24, was. Seri'a1 No;"I 28, 57.

. filament ha not been a Patented Sept. 8, 1914.

g'a's'e's, I seal the bulb, whereupon it will be found that the exterio, appearance of the ectedin'any artic-' ularly noticeable manner, and a sustantially perfect vacuum obtained, which will; be, practically maintained throughout the life of thelainp. If the lamp is to be used in an inclined position, or under circumstances subjectingit to jolts or jars, the filament may be attachedto the bulb at any.

place therein in mannersimilar to the wayin' ln'ch' carbon filaments for high tension 4 mp a sefi es d- I To eliminate the occluded gases (without materially reducing the oxid) from filaments consisting'of a mixture of oxid and osmium also'those wherein the osmium iscoated, with ofzrid, I proceed as'follows: I first" mount the,filain'nts in' the bulb, as before, by fusifoii. I then' rinse the bulb by passing a current of dry (such as nitrogen) through it I and thereupon partially exhaust it. I then pass a current of electricity throughthe' filamentsufficient' to first raise the filament to'a red heat, gradually-increasing the'current until the filament is raised to a yellowish White'hat, in' the meantime continuously, or from timeto time, increasing"the'vacuum. During this operation, the filamen gives ofi its occluded gases and a faint 'glrmmeringtakes place Within the bulb for a considerable period. As soonvas the development of gas ceases permanently, but ndt until then, I increase the strength of the current sufliciently to bring the filament to a bright-white heat, and, as soon as the resistance becomes constant, I seal the bulb. Caremust be taken, in this process,-t o pre: vent energeticglimmering, as otherwise the interior of the bulbwill be covered with a brownish coatingl i Theproc'ess just described for obtaining said filaments of associated osmium and oxid filaments free" from occluded gases maybe replaced" the following processv which re V quires less time: An osmium filament is first fastenedin'the lamp-base with osmium ce- YatentNo; 976,528, Nov," 29, 1910. It is,

then inserted within a closed receptacle and avacu'um isip'r odu'ce'd Within the receptacle.

Thefilameht is then raised to a'yellowish wlilte'lieat by the electric current. As soon I as glimmering-begins, nitrogen with some oxidizingagent, as, for instance, small quantities of air, (or; preferably, steam or.car-

bonic acid gas,) or similar gases or vapors, are adm tted, for the purpose of" unitm with the occluded gases as they are given 0 by the filament. soonas thisunion hastaken place, the vessel is filled with dry nitrogen. The'filament is then" coated with oxids and dried quickly, and the lamp base is united with the bulb, whereupon, to finish thelamp, itis'merely necessary to exhaust andv seal the bulb.

It will be noted that in the production of a' filament of associated osmium and oxid substantially free from occluded-"gases," the process has been conducted under'conditions filaments of associated osmium and oxid,- the fil menris first raised to a red heat and finally to a yellowish white heat, and the occluded gases g ven 01f, are continuously exhausted byJ-the vacuum pump; and it is n'otuntil the development of gas has entirely' ceased that a higher. temperature is employed. So also in the second method described for producing filaments of associated osmium and oxid: devoid 10f occluded gases,

' theo'ccjluded gases as for instance, hydrogen,

' drawn from. the oxid of the its ' filament.

carbonic acid, carbon vdioxid, and hydrocarbon gases are first eliminated from the osmium filament with which the method is started, before the oxids areap'plied to said The resulting filament in both cases is, therefore, a filament consisting substantially of osmium either admixed with. or coated with an oxid practically unreduced. I may so conduct the operation, however, as to produce a filament wherein the osmium is associated with or coated with a combina tion of varying composition, cording to the quantity of oxygen withoriginal filament of associated osmium and oxid treated. These combinations are produced either by .a partial reduction of the oxid with which the osmium is associated-or coated or by a partial oxidation of a metal-osmium filament. Externally these filaments exhibit a nearly metallic appearance and appearto be entirely homogeneous. Their conducti-g bility is, in general greater than that of the filaments of associated osmium and oxid from which they may be produced,,but less than that of the metallic osmium alloys. They occlude gases in about the same degree as do the osmium filaments themselves. Heated according .tothe first method above described for treating varying ac- 1 to a dazzling white heat in oacuo they do not glimmer and resist high temperatures. The production of these last mentioned filaments by the utilization of the occluded gases contained within the osmium has the advantage that not only are said gases quickly and effectually withdrawn from the filament and from the'bulb itself by the action of the vacuum pump, -where by the vacuum in the bulb is'attained with corresponding rapidity and with the assurance that it will be per- .manent, but also that the degree of the reduction may be predetermined and controlled with great accuracy. The process of producing the said filaments by obtaining a partial reduction of the oxids by the occluded gases i'squitesimilar to that for. the production of the filaments of associated osmium and oxid from which they may be derived., Ordinary filaments of associated osmium and oxid (for instance filaments consisting of osmium associated with thorium oxid) are first mounted, by fusion, in the lamp bulb. The bulb is then rinsed with dry gases and filledtherewith, whereupon it is connected with, the vacuum pump. and.

the exhausting. operation is begun. The

filament is then brought to a bright incandescence, the rather high resistanceof the filament remaining constant. The development of gas 'begins and eventually the lamp after a considerbegins to glimmer. When, able interval, the development of gas slack- "ens'and an almost complete vacuum exists in the bulb, the strength of the currentis increased until the filament is brought to'a dazzling white heat. Presently the resistance of the filament suddenly sinks, the temperature required "for reduction having been reached, whereupon a corresponding resistance mustbe switched in or the tension of the-current must be diminished. The development of gas then ceases and the glimmer becomes extinguished. The resistance gradually sinks stilllower, and after some time becomes constant. The filament contracts and the vacuum beingcompleted, the lamp is then to be sealed. ,According to the quantity of the gases present in the osmium filament at thetime of the beginning of the reaction, and accordingto the quantity of oxid present in the filament itself, the resulting conductibility of the filament is higher .or lower. Inasmuch as in practice, 'it is often desirable-to have a high resistance, I preferably give to the filament as high a percentage of oxid as possible. But, in' view of the factthat filaments with a high per.

centage of oxid require for their production high tensioncurrents and inasmuch as this percentage in many cases (particularly for thorium oxid) should not materially exceed fifty per cent. because the conductibility of the original oxid and osmium filaments in the cold diminishes as the percentage of oxid mium may be commingled with the oxid in thesaturating or coating solution-or emuli sion. When this process is correctly can, ried out it has the advantagepf making the filaments-denser, so that they will .not glimmermaterially during the subsequent-formato which the. lea mg m and to coat it increases, and 3 with even greater. rapidity .it

istherefore advisablenot to givea filament too high an .orig-inalperoentage of oxids,

it with the-oxid t i the,. tl 1jorium oxid is of advantage when they favorably influence, at white ineandescence,

but to afterward saturate It will be, of course, unde rstood that .os-

tion period in the lamp. The .oxid or mixrest sm um .aed pai app to filament for the purpose of saturat ng and coating the same 1s preferably, in the finest subdivision, made into an emulsion: 'The filament is thereupon dip ed into the emul sion throughout the ent re length of'the filament exceptin the terminal endsthereof wires are to'be "attached. The filament is then dried and again dipped in the emulsion, again drled 620., until the desired quantity of ox1d or Osmium and oxid has been added to it. If

the quantity to be applied to the filament is I rather large, it is advisable at intervals to insert the filament within a, protecting gas mixture and to bring it to a whlte heat therein. In this manner we obtain a core of better conducting oxid and osmium and a coating of less conductivity. Instead of .usingoxid and osmium filaments, it will, of course, be understood that filaments of pure osmium may be used; in the latter case, hoW- ever, it is advisable not to make the filaments toodense which may be readily guarded against by making the filament out of lime and osmium paste and by not heating the filament too high subsequently when it is being consolidated. In this instance, the saturation and coating of the filament takes place in the manner justdescribed and the further treatment of the saturate and coated filament, u to th completion of the lamp, is likewise t e same.

I have found that thorium oxid is the oxid best adapted for the production of these filaments of partly reduced oxid and osmium or partly oxidized osmium. It may, however, be entirely or partially replaced by oxid of zirconium, the ytterite earths and similar refractory oxids'whose partly reduced oxid when associated with osmium resists the high temperatures employed in practice and these substitute materials may be employed either alone or in admixture with each other in place of the thorium oxid,

although, as I have intimated, with less ad- -the more firmlywill be held the oxid which resists volatiliza'tion to a lesser degree. The admixture of these inferior oxids with the'candle power of the filament.

,Inlall of these filaments, osmium may be as ruthenium, iridium or rhodium, without essentially altering the operation. Such filaments, however, in case they contain considerable quantities of the metals referred to, have .nota very high capacity for resisting disintegration, Nevertheless, they are characterized by theremarkable property that, in spiteof a considerable percentage in osmium they do not, after a time give off osmium yapors when brought to white ineandescence'in the'op'en" air. r f

"Filaments produced in accordance with the processes hereinbefore set forth are, by reasonof the practical elimination of the occluded'gases, homogeneous and wholly or substantially free from glimmering when brought to white incandescence.

Having thus described my invention, what I claim'is:

1. A filament for electric vacuum lamps, containing osmium, and oxid of a rare metal earth, and a supplcmentaloxid, said filament containing, at ordinary temperatures, substantially only such gases as remain' occluded therein at white incandescence. r

2. A filament for electric vacuum lamps, containing osmium, and partly reduced oxid compounds of a supplemental metal.

containing osmium, and partly reduced oxid compounds of a rare metal earth.

' i. A filament for electric vacuum lamps, containing osmium, partly reduced oxid compounds 'of'a' rare metal earth, and an oxid of a supplemental metal.

containing osmium, and partly reduced oxid compounds of thorium.

6. A filament for electric vacuum lamps,

containing osmium, and partly reduced oxid compounds of a supplemental metal, said filament containing, at ordinary tempera tures, substantially only such gases as remain occluded therein at white incandescence.

- 7. A filament for electric vacuum lamps, containing osmium, and partly reduced oxid compounds of a rare metal earth, said filament containing, at ordinary temperatures, substantially only such gases as remain occluded therein at white incandescence.

8. A filament for electric vacuum lamps, containing osmium, partly reduced oxid compounds of a rare metal earth, and an oxid of a supplemental metal, said filament the oxidwhich. fully resists volatilization,

replaced in part by otherplatinum metals,

5. A filament for electric vacuum lamps,

3. A filament for electric vacuum lamps,

' containing, at ordinary temperatures -sub- 'stantially' only such gases as remam joc eluded therein at White incandescencet 9.v A. filament for electric vacuum lamps,-

' containing osmium, and partly reduced oxid compounds of thorium, said filament com taining at ordinary temperatures, substantially'only' such gases as remain occluded therein at white incandescence.

containing osmium, andpartly reduced oxid ""10.'Afi1ament for electric vacuumlam s containing osmium; partly reduced joxid' compounds of a su p lement al'metal, and an exterior coating 0 oxid, said. exterior coating being of less conductivity than the partly reduced oxidl 12. A filament for electr c vacuumlamps, containing osmium, partlyreduced 'oxid compounds of asupplemental metal said a partly reduced oxid being impregnated with an additional quantity of oxid and having a coating of said additional oxid.

' In witness whereof I hereuntoattach my signature, in' ing witnesses; DB. CARL AUER VON WELSBACH.

the presence of two subscrib- "Witnesses:

'ADOLFGALLIA,

L; HALILINQIER. 

